[DeTomaso] Compression ratio question

Dagny Kristine Bakken dagny-kr at online.no
Sat Sep 22 17:43:46 EDT 2007


Thanks for the input:) I found a good site clarifying what we are talking
about for those interested http://www.empirenet.com/pkelley2/DynamicCR.html


Best regards
Øyvind



-----Opprinnelig melding-----
Fra: Göran Malmberg [mailto:hemipanter at hemipanter.se] 
Sendt: 22. september 2007 21:56
Til: Dagny Kristine Bakken; detomaso at realbig.com
Emne: Re: [DeTomaso] Compression ratio question

A great deal, as a big cam has a lot overlap the cylinder will not build
very much presure at lower rpm:s, and defineatly not at cranking speeds.
Therfore you must measure cylinder pressure at an rpm at which the cam is
breathing at its best, provided you want to know the cylinder filling
ability of the engine. To compare cylinder condition to each other, it
dosent matter.
You ask how much it matters. The same amount as the difference in Tq output
depending on different engine combinations.
Goran



and it right,the compression pressure in a fresh engines cylinder is the
result of compression ratio + eventually charging from the intake air ,
minus pressure escaped from bypassing pistonrings,minus pressure lost from
the cams exhaust overlap to help get rid of the exhaust.I understand that
the rpm. and thereby the airspeed will affect this,but how much?
One thing i know for sure ,is that its very important to have the throttle
wide open when measuring the compression pressure,as you otherwise build up
vacum on the intake side and get wrong result :)

Øyvind Bakken
_______________________________________________

Detomaso Forum Managed by POCA

Archive Search Engine Now Available at http://www.realbig.com/detomaso/

DeTomaso mailing list
DeTomaso at list.realbig.com
http://list.realbig.com/mailman/listinfo/detomaso







More information about the DeTomaso mailing list